FIG. 1 is a diagram showing one example of a prior art liquid crystal display apparatus 1.
The liquid crystal display apparatus 1 shown in FIG. 1 comprises a liquid crystal panel 2 and a point light source 9. The liquid crystal panel 2 is constructed by sandwiching a liquid crystal between substrates using a sealing member 3 and a seal 4. Light radiated from the point light source 9 diffuses into the liquid crystal panel 2 as shown by arrows 5. However, in regions 6 and 8 in the figure, the light is not sufficiently diffused, and brightness is reduced. On the other hand, in region 7 in the figure, a bright spot may be produced due to increased brightness due to the region being close to the light source. In this way, the prior art liquid crystal display apparatus 1 has had a problem in that the brightness is not uniform over the entire display area.
In view of this, an attempt has been made to solve the problem of brightness nonuniformity by mixing light scattering particles into the sealing member on the light source side and thereby causing the light to be scattered (for example, refer to patent document 1). When such light scattering particles are mixed into the sealing member on the light source side, the light is scattered when passing through the sealing member on the light source side. While this serves to prevent the brightness from being reduced in the regions 6 and 8 in FIG. 1, the light is not spread throughout the liquid crystal panel, and the brightness is reduced in regions far from the light source. On the other hand, if a sufficient number of light scattering particles are not mixed into the sealing member on the light source side, the light is not sufficiently scattered, resulting in an inability to prevent reduced brightness in the regions 6 and 8 in FIG. 1.
Another attempt has been made to solve the problem of brightness nonuniformity by providing prescribed spacing between the light source and the liquid crystal and by forming a frosted glass-like rough surface on a glass substrate between them, thereby diffusing the light through the rough surface (for example, refer to patent document 2). This, however, has involved a problem in that not only is it difficult to roughen only the designated portion of the substrate, but cost also increases.
A further attempt has been made to solve the problem of brightness nonuniformity by providing prescribed spacing between the liquid crystal and the effective display area and by providing therebetween a polymer-dispersed liquid crystal or a scattering segment formed from a polymer-dispersed liquid crystal, thereby causing the light to be scattered through the liquid crystal itself or through the scattering segment (for example, refer to patent document 2). This, however, has involved a problem in that it requires the use of an expensive polymer-dispersed liquid crystal material, and to form the scattering segment from the polymer-dispersed liquid crystal, the liquid crystal has to be sealed separately. It also has been difficult to effectively utilize the light by simply providing the polymer-dispersed liquid crystal between the liquid crystal and the effective display area.
Patent document 1: Japanese Unexamined Patent Publication No. H11-183888 (FIG. 1)
Patent document 2: Japanese Unexamined Patent Publication No. 2000-162672 (FIGS. 4, 5, and 6)